Islamic State of Iraq and Levant (ISIL) fighters fleeing the battlefield in Libya may try to hide among asylum-seeking migrants crossing the Mediterranean in smugglers’ boats, Italian intelligence officials warned.

A sustained assault by forces loyal to Libya’s government, backed by U.S. fighter jets and drones, has driven hundreds of ISIL jihadists from Sirte. Libyan officials report that three-quarters of the city has now been liberated, a year after it was first seized by ISIL.

Some 30,000 migrants have crossed the Mediterranean from Libya to Italy this year.

Italian intel said there is now a “greater risk” that some terrorists could attempt to pass themselves off as migrants or refugees and, if they reached Italy, plan attacks on targets in Europe.

“For a long time it seemed improbable, if not impossible, that Daesh (ISIL) would put its fighters on migrant boats, putting at risk men in whom it had invested time and money,” said Giacomo Stucchi, the head of Italy’s intelligence committee. “But now there is total chaos, and in trying to escape from Libya those who are not heading south (into the desert) could try to cross by sea to Europe.”

Stucchi added that the fleeing jihadists are “loose cannons, men on the run. We need to understand their intentions – whether they want to disappear without trace, or whether they want to continue fighting in the name of their cause.”

Italy was alerted to the increased threat of terrorists attempting to cross to Europe when it was revealed that ISIL fighters escaping Sirte had left behind graffiti in which they described the city as “the port of the Islamic State – the starting point for Rome.”

“There’s always a risk of people trying to infiltrate in this way. But the priority for us was to liberate Sirte. This is a great victory for the forces of the coalition and the (UN-backed) government of (Fayez) Al-Sarraj,” said Pier Ferdinando Casini, the president of the foreign affairs committee in the Italian Senate.

Italy last week said it tightened security controls at commercial ports, with passengers and vehicles boarding ferries in cities such as Genoa, Palermo and Bari facing long delays.